001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.bcel.verifier.structurals; 018 019/** 020 * This class represents a JVM execution frame; that means, a local variable array and an operand stack. 021 */ 022 023public class Frame { 024 025 /** 026 * For instance initialization methods, it is important to remember which instance it is that is not initialized yet. It 027 * will be initialized invoking another constructor later. NULL means the instance already *is* initialized. 028 * 029 * @deprecated Use the getter/setter to access the field as it may be made private in a later release 030 */ 031 @Deprecated 032 protected static UninitializedObjectType _this; 033 034 /** 035 * @return the _this 036 * @since 6.0 037 */ 038 public static UninitializedObjectType getThis() { 039 return _this; 040 } 041 042 /** 043 * @param _this the _this to set 044 * @since 6.0 045 */ 046 public static void setThis(final UninitializedObjectType _this) { 047 Frame._this = _this; 048 } 049 050 /** 051 * 052 */ 053 private final LocalVariables locals; 054 055 /** 056 * 057 */ 058 private final OperandStack stack; 059 060 /** 061 * 062 */ 063 public Frame(final int maxLocals, final int maxStack) { 064 locals = new LocalVariables(maxLocals); 065 stack = new OperandStack(maxStack); 066 } 067 068 /** 069 * 070 */ 071 public Frame(final LocalVariables locals, final OperandStack stack) { 072 this.locals = locals; 073 this.stack = stack; 074 } 075 076 /** 077 * 078 */ 079 @Override 080 protected Object clone() { 081 return new Frame(locals.getClone(), stack.getClone()); 082 } 083 084 /** 085 * 086 */ 087 @Override 088 public boolean equals(final Object o) { 089 if (!(o instanceof Frame)) { 090 return false; // implies "null" is non-equal. 091 } 092 final Frame f = (Frame) o; 093 return this.stack.equals(f.stack) && this.locals.equals(f.locals); 094 } 095 096 /** 097 * 098 */ 099 public Frame getClone() { 100 return (Frame) clone(); 101 } 102 103 /** 104 * 105 */ 106 public LocalVariables getLocals() { 107 return locals; 108 } 109 110 /** 111 * 112 */ 113 public OperandStack getStack() { 114 return stack; 115 } 116 117 /** 118 * @return a hash code value for the object. 119 */ 120 @Override 121 public int hashCode() { 122 return stack.hashCode() ^ locals.hashCode(); 123 } 124 125 /** 126 * Returns a String representation of the Frame instance. 127 */ 128 @Override 129 public String toString() { 130 String s = "Local Variables:\n"; 131 s += locals; 132 s += "OperandStack:\n"; 133 s += stack; 134 return s; 135 } 136}